Tuesday, March 18, 2008

Interview with Ralph Moir: Part I

Introduction: I wrote Dr, Ralph Moir last week, seeking an email interview. Dr. Moit was an extremely distinguished scientist at Lawerence-Livermore Laboratory, and a personal associate of Dr. Edward Teller. Dr. Moir was extremely gracious in answering all of my questions. I jave split the three pasts of the interview into three separate posts. The first questions address Dr. Moir's work with fission/fusion hybred reactors.

On Mar 13, 2008, at 9:49 AM, Charles Barton wrote:

Dear Dr. Moir, There are numerous questions I would like to ask you. This would be of course contingent on your willingness to spend the time required to respond to my questions. I take the view that scientist are people who work on important questions, and their views should be known to a broader public. I have posted a number of my father's public papers along with an account of his career at ORNL on my blog, Nuclear Green. I have also given a considerable focus to the writings and career of Alvin Weinberg. Since you are a senior scientist, your knowledge and experience should be of considerable public interest. If you so choose, I would very much appreciate if you answer some or all of these questions.

During much of your own working career, you worked on the fusion/fission hybrid concept. I have a number of questions in connection with that:

1. Do you still think that concept is viable?

2. What would see as its strengths and weaknesses?
Fusion holds the promise yet to be full filled of providing a supply of neutrons that can be used to produce fissile fuel for fission reactors. Even if fusion cost twice that of fission per unit of thermal power produced, its fuel would be competitive with mined uranium at $200/kg. Fusion will be even more competitive as its cost come down. This produced fuel can be used in fission reactors to completely burn up the fertile fuel supply, that is depleted uranium or thorium. Its weakness is fusion is not here and past slow progress suggests future progress might be slow. Furthermore, we are not assured that fusion's costs will be less than twice that of fission.

That fusion can produce or breed fissile fuel is an advantage and simultaneously any facilities must be guarded against their misuse towards making fissile material for unauthorized explosives.

3. What technical advantages, if any would you see for a fusion/fission hybrid over a conventional molten salt reactor?

A conventional molten salt reactor can produce almost all of its own fuel but needs initial fuel for start up and needs some make up fuel and also some fuel to be used to burnout certain wastes. So the fusion/fission hybrid can be this fuel supplier. In this way the combination of a hybrid fuel supplier and molten salt burners can supply the planets power for many hundreds or even thousands of years at an increased nuclear power level enough to make a big impact in decreasing carbon usage. Such a combination might have one hybrid fusion fission reactor for every fifteen fission reactors.

If a hybrid reactor produces both fuel and power by fissioning this fuel insitu, I am afraid the system will be uneconomical relative to the combination of a fuel producer and separate burner fission reactors and relative to other fission reactors.

4. In what timeframe might we expect to see an technically and economically viable product?

So far fusion concepts that are approaching the feasibility stage suffer from being very expensive. Tokamak magnetic fusion and laser fusion facilities are very expensive making "productizing" uneconomical based on our present state of the art. The next tokamak called ITER might be built and tested in 15 years and with advances the projected costs in a follow-on might be low enough that a product or viable product can come out after another 15 years or 30 years from now.

The laser fusion facilities are also too expensive but with advances in the next five years a follow on set of facilities might be an economical product in another 15 years or 20 years from now. A key to progress in fusion is getting better performance in smaller lower cost facilities.

1 comment:

M. Simon said...

We need to put more effort into small fusion:

WB-7 First Plasma

Time line on a normal schedule? Five years to a 100 MW Demo.

An accelerated schedule (cost no object - within reason - Manhattanized) could get us grid power in 3 to 4 years.

It is amazing the number of bright people in the business who haven't heard of this development.


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